Lung cancer, a malignant lung tumor characterized by uncontrolled cell growth in tissues of the lung, is the leading cancer killer in both men and women in the US. More people die from lung cancer than from breast cancer, prostate cancer and colon cancer combined globally. Nevertheless, the five-year survival rate in early stage non-small cell lung cancer (NSCLC) is above 50%. The five-year survival rate drops to below 5% in NSCLC patients with metastatic disease. Although early detection can save lives, screening tests for high-risk individuals are still lacking. Helical low-dose computerized tomography (LDCT) has been used for screening in high-risk populations. However, there are multiple drawbacks associated with LDCT screening including false-negative, false-positive, radiation exposure, and financial cost. Currently no non-invasive test for lung cancer using body fluids such as blood and sputum is available.
In addition, lung nodules are commonly detected on CT. It is reported that up to 51% of smokers 50 years or older have pulmonary nodules on CT. In some cases, it is difficult to differentiate malignant nodules from benign nodules. It is recommended that these undetermined nodules should be followed up with serial CT, which increases substantial radiation exposure to the individuals and financial cost. A blood test for differentiating malignant and benign nodules will be highly beneficial to patients.
Thus, there are urgent needs for blood tests for lung cancer detection and for distinguishing lung cancer from benign lung nodules.